The purpose of this project is to determine how nerve fibers exert their trophic effect on end-organs. In one study, denervated tongue was reinnervated by sensory nerve fibers which normally do not innervate taste buds. These sensory fibers were able to induce taste bud formation. In muscle, it was found that denervated muscle in the rat with congenital absence of the peroneal nerve could become reinnervated by a normal nerve indicating that an abnormality in the nerve and not muscle is responsible for the neurological defect. In tissue culture it was observed that a soluble protein could be extracted from 21-day degenerating nerve, which like a protein from intact nerve, could maintain muscle cells in culture (joint work with Dr. Oh). Studies with muscle allografts bearing major transplantation antigens indicated that these allografts could survive and become reinnervated in recipient rats rendered immunological tolerant with bone marrow but not lymph node cells.